OP will ask the obvious, did you price out the rental with the new, correct time you want to pick it up? Might want to give UT a call & ask
my understanding is all rental car companies have varying policies on this early & late pickup changes. Buried in their websites or you could call & verify the specifics.
I‘ve never had a problem picking up our reserved vehicle a bit earlier/later if just an hour or so. Once we had a flight delayed for almost 6 hours, I had no problem upon arrival, however, I had flight info linked to the res to prove why we were not on time. NatIonal honored that rate, however, it was before the pandemic shortage.
inventory is still rather limited at MCO at times (this going by what I’m seeing on the Alamo aisle and rates they all are charging).
You may very well find yourself waiting for a car…as in one might need to be returned, cleaned etc. I’ve asked before, was told they try to have them ready an hour ahead of time.